The present invention relates to a process for producing optically active 1,2-diols.
The optically active 1,2-diols are useful as various pharmaceutical preparations and optically active, biologically active substances, as well as intermediates of their derivatives.
For example, cis-(1S,2R)-dihydroxyindane or trans-(1R,2R)-dihydroxyindane can be an important starting material of Crixivan used as an anti-AIDS drug because of its inhibitor activity on proteolytic enzymes for AIDS virus (J. Med. Chem., 34, 1228 (1991)).
Known methods of microbially producing optically active 1,2-diols include, for example, a method of reacting indene along with a cultured microorganism of the genus Pseudomonas (J. Chem. Soc., Chem. Commun., 339 (1989); J. Chem. Soc., Chem. Commun., 117 (1995)), a method of adding a derivative such as indene, 1,2-dihydronaphthalene or the like to a culture of Mortierella isabellina to convert it into a hydroxide (Bioorg. Med. Chem., 2, 439 (1994)), a method of using as a starting material optically active 2-bromo-1-hydroxyindane generated upon asymmetrical reduction of 2-bromoindane-1-one with Cryptococcus macerans (J. Org. Chem., 43, 4540 (1978)), and a method of stereoselectively hydrolyzing 1-methoxy-2-acetoxyindane in a culture of Rhizopus nigricans (J. Org. Chem., 49, 675 (1984)).
Further, known methods of synthesizing optically active 1,2-dihydroxyindane derivatives by chemical synthesis include a method of reacting 2-bromo-1-hydroxyindane in the presence of acetic acid or acetic acid and water (J. Chem. Soc. Perkin Trans. I., 2767 (1982)) and a method of oxidatively hydrating indene (Synthesis, 1142 (1985)).
However, these conventional methods, particularly chemical synthetic methods, have the problems that the starting materials are expensive, the operation is cumbersome and the yield is low because of the multiple-step reaction, or the optical purity of the resulting 1,2-dihydroxyindane is low, while the microbial methods also have the problem that the range of utilizable microorganisms is limited.
The object of the present invention is to provide a process for producing optically active 1,2-diols efficiently by microorganisms not used in the conventional microbial methods.
That is, the present invention encompasses:
1. A process for producing optically active diols represented by the general formula (II): 
wherein R1 represents (CH2)n, CHxe2x95x90CH, O, S or NH whereupon n is an integer of 1 to 4, and R2 represents hydrogen, C1-6 alkyl, C1-6 alkoxy, C1-6 alkoxy-carbonyl, hydroxy, carboxy, halogen, nitro or amino, which comprises treating compounds represented by the general formula (I): 
wherein R1 and R2 have the same meanings as defined above, with a culture of a microorganism belonging to the genus Rhodococcus, Bacillus, Brevibacterium or Gordona and being capable of stereoselectively diolating a double bond in ring A, or with said microorganism itself, or with a treated material from said microorganism.
2. The process according to item 1 above wherein the microorganism capable of stereoselectively diolating a double bond in ring A is a microorganism belonging to the genus Rhodococcus.
3. The process according to item 2 above wherein the microorganism belonging to the genus Rhodococcus is Rhodococcus rhodochrous ATCC 21199.
4. The process according to item 2 above wherein the microorganism belonging to the genus Rhodococcus is Rhodococcus rhodochrous ATCC 21198.
5. The process according to item 1 above wherein the microorganism capable of stereoselectively diolating a double bond in ring A is a microorganism belonging to the genus Bacillus.
6. The process according to item 1 above wherein the microorganism capable of stereoselectively diolating a double bond in ring A is a microorganism belonging to the genus Brevibacterium.
7. The process according to item 1 above wherein the microorganism capable of stereoselectively diolating a double bond in ring A is a microorganism belonging to the genus Gordona.
8. The process according to item 1 above wherein substrate-adsorptive carriers are added to the reaction solution.
9. A process for producing optically active diols represented by the general formula (II): 
wherein R1 represents (CH2)n, CHxe2x95x90CH, O, S or NH whereupon n is an integer of 1 to 4, and R2 represents hydrogen, C1-6 alkyl, C1-6 alkoxy, (C1-6 alkoxy)-carbonyl, hydroxy, carboxy, halogen, nitro or amino, which comprises treating compounds represented by the general formula (I): 
wherein R1 and R2 have the same meanings as defined above, with a culture of Mortierella vinacea, or with said microorganism itself, or with a treated material from said microorganism.
10. The process according to item 9 above wherein substrate-adsorptive carriers are added to the reaction solution.
In the definition of each group in the compounds shown in the general formula (I) or (II), the alkyl moiety in C1-6 alkyl, C1-6 alkoxy and (C1-6 alkoxy)-carbonyl may be straight-chain or branched insofar as it is alkyl containing 1 to 6 carbon atoms, and examples of such alkyl include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl and hexyl. The halogen refers to each atom of fluorine, chlorine, bromine or iodine.
The purity of the compounds represented by the general formula (I), which are used in the present invention, is not particularly limited, and those of high purity or low purity may be used. Impurities are preferably compounds not adversely affecting the growth and existence of the microorganism and the enzyme activity, but there is no particular limit insofar as their influence is negligible.
The compounds represented by the general formula (I) are preferably those wherein R1 is (CH2)n, more preferably those wherein R1 is CH2 or (CH2)2.
The microorganisms used in the present invention may be any microorganisms belonging to the genus Rhodococcus, Bacillus, Brevibacterium or Gordona, or Mortierella vinacea. 
The microorganisms belonging to the genus Rhodococcus include e.g. Rhodococcus rhodochrous ATCC 21198, Rhodococcus rhodochrous ATCC 21199, Rhodococcus ruber JCM 3205, Rhodococcus sp. IFM 18 and Rhodococcus globerulus ATCC 25714.
The microorganisms belonging to the genus Bacillus include e.g. Bacillus megaterium IAM 1032 and Bacillus pasteurii ATCC 11859.
The microorganisms belonging to the genus Brevibacterium include e.g. Brevibacterium acetylicum ATCC 953.
The microorganisms belonging to the genus Gordana include e.g., Gordana rubropertinctus ATCC 27863 (equivalent to Rhodococcus ruber JCM 3205).
Mortierella vinacea includes e.g. Mortierella vinacea TKBC 1102.
Rhodococcus rhodochrous ATCC 21198, Rhodococcus rhodochrous ATCC 21199, Rodococcus globerulus ATCC 25714, Bacillus pasteurii ATCC 11859, Brevibacterium acetylicum ATCC 953 and Gordona rubropertinctus ATCC 27863 are stored in American Type Culture Collection (ATCC) in 12301 Parklawn Drive, Rockville, Md. 20852, U.S.A. and also appear in a catalogue.
Rhodococcus ruber JCM 3205 is stored in Japan Collection of Microorganisms (JCM) in the Institute of Physical and Chemical Research (RIKEN) in Hirosawa 2-1, Wako-shi, Saitama, JP and also appears in a catalogue.
Rhodococcus sp. IFM 18 is stored in Research Center for Pathogenic Fungi and Microbiol Toxicosis, Chiba University (formerly Institute of Food Microbiology) in Inohana 1-8-1, Chuo-ku, Chiba-shi, Chiba, JP and also appears in a catalogue.
Bacillus megaterium IAM 1032 is stored in IAM Culture Collection (IAM), Center for Cellular and Molecular Research, Institute of Molecular and Cellular Biosciences, the University of Tokyo in Yayoi 1-1-1, Bunkyo-ku, Tokyo, JP and also appears in a catalogue.
Mortierella vinacea TKBC 1102 is stored in TKBC Culture Collection (TKBC), Institute of Biological Science, University of Tsukuba in Tennodai 1-1-1, Tsukuba-shi, Ibaraki, JP and also appears in a catalogue.
Among the microorganisms described above, preferable microorganisms include microorganisms belonging to the genus Rhodococcus, particularly Rhodococcus rhodochrous such as Rhodococcus rhodochrous ATCC 21198 and Rhodococcus rhodochrous ATCC 21199.
In the present invention, the compounds of the general formula (I) above are treated with a culture (e.g. a culture liquid) of the microorganism, the microorganism itself or a treated material from the microorganism (e.g. a material from the disrupted microorganism, an extract from the microorganism, or a crude or purified enzyme from the microorganism).
As the form of this treatment reaction, mention is made of e.g. a method of directly adding the substrate, that is, the compound of the general formula (I) above, to a culture liquid of the growing or grown microorganism, a method of suspending the isolated grown microorganism in a buffer and then adding the substrate thereto, and a method of immobilizing the microorganism in a usual manner, then floating it in a stirring chamber or charging it into a column, and adding the substrate thereto.
The substrate may be added all at once, but preferably added in portions. Alternatively, a continuous reaction method of continuously adding the substrate while continuously recovering the product can also be used.
Usually, the composition of the medium for culturing the microorganism used in the present invention may be any suitable medium in which the microorganism can grow, but the following composition can be mentioned as a preferable example. That is, the carbon source is glucose, mannitol or a mixture thereof, and the nitrogen source is yeast extract, corn steep liquor, peptone, meat extract or a mixture thereof. Further, inorganic materials such as common salt and manganese sulfate are preferably added.
Culture of the microorganism used in the present invention may be conducted in a usual manner, for example at pH 5 to 9, preferably 6 to 8, at a culture temperature of 20 to 40xc2x0 C., preferably 25 to 30xc2x0 C., and aerobically for 24 to 72 hours, but when the reaction is conducted by adding the substrate to the culture liquid, culture may be continued for 300 hours or more.
When the reaction is conducted by adding the substrate to the culture liquid, it is preferable that oil such as soybean oil or silicon oil is added at a concentration of 5 to 50%, preferably 10 to 20%, or a carrier capable of adsorbing the substrate, for example adsorptive resin (e.g. HP-20 resin, Mitsubishi Chemical) or dried yeast (Ebios(trademark), Asahi Beer Yakuhin), is added at a concentration of about 0.5 to 10%, preferably 1 to 5%, in order to prevent the vaporization of the substrate or to avoid the inhibition of growth by the substrate.
When the microorganism is reacted after harvested, it is preferable to use the microorganism grown by adding the compound of the general formula (I) or its reduced compound such as indene, indane, naphthalene or dihydronaphthalene as an inducer for enzyme activity during culture.
Culture is conducted preferably at a reaction temperature of 15 to 50xc2x0 C., preferably 20 to 30xc2x0 C. and at pH 5 to 10, preferably 6 to 8. The substrate may be added all at once, but preferably added in portions, and when added to the medium, the substrate is adjusted to a concentration in the range of 0.02 to 1.0%, after which it can be added little by little as the reaction proceeds. Further, in the case of the reaction with the microorganism or with the immobilized microorganism, the concentration of the substrate is regulated in the range of 0.1 to 1.0%, after which the substrate can be added little by little as the reaction proceeds. The reaction is conducted usually under shaking or stirring. Although the reaction time varies depending on the concentration of the substrate, the density of the microorganism and any other reaction conditions, the reaction time is preferably selected such that the reaction in the case where the substrate is added to the culture medium is finished in 100 to 300 hours or more, or the reaction with the microorganism or with the immobilized microorganism is finished in 6 to 72 hours. In respect of yield, it is preferable that while the reaction is analyzed by taking an aliquot of the reaction solution, the reaction is terminated when the reaction stops.
The reaction with the microorganism isolated after culture or with the immobilized microorganism may be conducted in a sealed vessel in which an air layer corresponding to a stoichiometrically necessary amount of oxygen is kept to prevent the vaporization of the substrate.
To recover the thus obtained optically active 1,2-diol from the reaction solution, general techniques, for example extraction with organic solvent such as ethyl acetate or isopropyl acetate, can be used. For this recovery, the microorganism may be removed by centrifugation or filtration as necessary prior to extraction of the desired product. Alternatively, after removal of the microorganism from the reaction solution, the desired product may be recovered by passing the solution through a column packed with suitable adsorptive resin (e.g. SP207 resin, Mitsubishi Chemical) and then eluting the adsorbed product with a suitable solvent such as acetonitrile and methanol.
The crude extract thus obtained is dehydrated over anhydrous sodium sulfate etc., and the solvent is removed under reduced pressure whereby crude optically active 1,2-diol can be obtained. It can be further purified by recrystallization after suspended in a solvent such as ethyl acetate or through various kinds of chromatography.